Increases in tractor size/tires/tracks/mass are all resulting in higher steering force requirements. Steering force is limited by the hydraulic pressure available to the steering circuit and/or the size of the steering actuators. Increasing steering pressure is the most cost effective way to increase steering capacity as it requires minimal modification to the steering valve and chassis components. Traditionally, a single spool/single pressure margin priority valve with a load sense relief feature is used to provide oil to a hydraulic steering circuit. The load sense relief valve is used to prevent the priority valve from blocking flow to low priority hydraulic functions when steering pressure reaches the relief setting. This approach reduces the maximum pressure available at the steering valve inlet to less than 90% of the maximum pump outlet pressure.
It would be desirable to enable the steering circuit to utilize the maximum pump pressure.